The Surprising News About Vehicle Emissions

DANIEL SPERLING: The United Nations Intergovernmental Panel on Climate Change (IPCC) met last month in Berlin to finalize its scientific assessment of solutions to curb greenhouse gas emissions. One of the key takeaways in the report is the opportunity for large emission reductions in the transportation sector.

Transportation is often thought to be the most intractable sector for reducing energy use and greenhouse gas emissions. Globally, the transport sector has steadily increased its share of total energy use, reaching 27% in 2010. The IPCC report, for which I contributed to the transport chapter along with my UC Davis colleagues Lew Fulton and Richard Plevin, breaks with past reports in articulating a more optimistic view of what is possible.

As the IPCC report notes, this shift toward more efficient vehicles, combining with slowing growth in light duty vehicle demand, is already producing a leveling off of oil demand, with consumption expected to head downward in the coming decades. In its 2013 Energy Outlook, even oil giant BP is projecting that oil demand has peaked in the OECD.

Perhaps the greatest challenge to decarbonization of the transportation sector is the expected high rate of return on investments in carbon-laden fuels by wealthy fossil-fuel companies. The oil sector is poised for a productivity revival based on new technologies for recovering unconventional oil and gas from shale formation. Environmental activists have focused on this carbonization by calling for divestiture from fossil fuel company shares. While shareholder movements of this sort have not been shown to have demonstrable lasting impact, policies targeting coal and oil company shareholder returns from high carbon fuels could prove an effective new area of regulation. But consumers will only embrace such measures if low carbon fuel alternatives flourish.

California has played a pivotal role in promoting the adoption of low carbon fuel technologies. It has done so through a combination of policy approaches, including a carbon cap and trade market, electric car mandate, investments in alternative fuel infrastructure, and fuel standards that force decarbonization over time. The results so far have been mixed but have pushed and pulled low-carbon technologies into the marketplace. Research from the Institute of Transportation Studies at the University of California, Davis highlights the importance of a portfolio approach in reducing energy use and greenhouse gas emissions. The key features of a low-carbon pathway include much more efficient cars and trucks, transition to electric and hydrogen energy for cars and other modes, and advanced biofuel use in long haul trucks and planes. The ITS Davis scenarios study shows that a 60% to 80% reduction in greenhouse gases in the transportation sector is possible by 2050, and that many of the changes would result in cost savings to consumers.